The present invention is directed to a chin implant for a human mandible and, more particularly, is an improvement of my invention as embodied in U.S. Pat. No. 4,888,018 (1989), entitled Method For Positioning and Securing a Chin Implant. The instant invention relates to an implant which is compatible for use with the method as taught in said patent.
Heretofore, chin implants of a resilient or silastic material (such as silicone) have been applied, during surgery, to the exposed mandible and retained in position by re-assembled skin tissue to enclose and engage the implant. One difficulty with this procedure, which is addressed by my above referenced patent, has been that during and after healing, such implants have been known to become mechanically displaced from the desired central location on the mandible. Also, in some instances, the pressure of the implant against the mandible has resulted in a re-absorption process of the silicone by the bone. This process is sometimes referred to as bone re-absorption and is due to a piezoelectric effect at the bone-implant interface.
The instant invention relates to an implant which reduces the bone-implant interface and, additionally, teaches the use of an implant, generally similar in geometry to the implant taught in my said U.S. Pat. No. 4,888,018, however, having a so-called dual durometer characteristic at the point of the chin, that is, in the outer surface of the mandible.
Other prior art respecting the present invention is U.S. Patent, is U.S. Pat. No. 3,720,959 (1973) to Hahn; U.S. Pat. No. 4,344,191 (1982) to Wagner; and U.S. Pat. No. 4,439,115 (1984) to Small. Related foreign references, know to me are French Patent No. 2,447,182 (1980) and USSR Patent No. 0637118 (1978).
None of the above, or other prior art known to me teaches a chin implant of the disclosed type capable of suspension above the periostium of the chin in the manner taught herein. Further, no prior art known teaches the use of a dual durometer pad, at the outward point of a prosthetic chin, to simulate the fat pad at the point of the chin.